This pertains to the field of keeping oneself or another clean while and after urinating, defecating or otherwise excreting, in public or private use facilities such as lavatories and baby changing stations.
The traditional approach to cleaning one's own person is to sit down on a toilet seat, to excrete, and then to use dry toilet paper to wipe one's affected skin, and then throw that soiled toilet paper down the toilet. This is what most people do most of the time in North America.
An extension to this approach is to this is to cover in some way the toilet seat or other surface which will touch the skin, thereby attempting to prevent skin from touching excreta and other debris already present on the toilet seat or other surface.
The traditional approach to cleaning oneself or somebody else who has soiled himself and needs to be cleaned, is to remove a soiled diaper, other apparel or both, to wipe clean that individual's affected skin, and then to dispose properly of the soiled diaper, other apparel, and the toilet paper or other implement used for wiping. A lavatory and its toilet, or similar use facility, are often but not always pertinent to this cleaning.